1. Field of the Invention
The present invention relates to a shooting apparatus which images a subject light on an image pickup element to produce an image signal, and to a lens barrel capable of changing a length thereof.
2. Description of the Related Art
In recent years, in addition to cameras for taking an exposure on a conventional silver-salt film, digital cameras have rapidly become widespread. Such a digital camera includes an image pickup element such as a CCD image pickup element or an MOS image pickup element, and which forms an image of a subject on the image pickup element and produce an image signal.
In this digital camera also, it is strongly required to enhance the shooting performance and carrying-easiness. There is a digital camera having a lens barrel incorporating, therein, a shooting lens comprising lens groups. In this digital camera, the focal length is variable so that shooting at desired angle of view can be carried out, and in order to enhance the carrying-easiness of the digital camera, the lens barrel is retracted in a camera body such that distances between the lens groups constituting the shooting lens become shorter than the minimum necessary distance required for shooting at the time of non-shooting, and the lens barrel is advanced such that the distances between the lens groups become the minimum necessary distance required for shooting at the time of shooting (see Japanese Patent Application Laid-open No. 5-34769).
There is a widely employed shooting lens having a variable focal length, the shooting lens includes three or more lens groups, a focus lens is disposed as the last lens group in the optical axis direction, the focus lens is moved in the optical axis direction to adjust a focus. Usually, a member for controlling a light amount such as a shutter or aperture is provided between the front lens group and the rear lens group or between the rear lens group and the focus lens. In recent years, a distance between the lens groups or a distance between the lens group and the light amount control member such as the shutter is shortened as short as possible to retract the lens groups so that the thickness of the camera is reduced and carrying-easiness is further enhanced. In the future, the thickness of the camera may further be reduced by retracting any of the lens groups constituting the shooting lens from the optical axis. However, there is a limit for reducing the thickness.